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Abstract Having powerful antibacterial and antioxidant effects, zinc oxide and manganese oxide nanomaterials are of great interest. Here we have synthesized manganese oxide decorated zinc oxide (MZO) nanocomposites by co-precipitation method, calcined at different temperatures (300–750 °C) and studied various properties. Here the crystalline structure of the nanocomposite and phase change of the manganese oxide are observed with calcination temperature. The average crystalline size increases and the dislocation density and microstrain decrease with the increase in calcined temperature for the same structural features. The formation of composites was confirmed by XRD pattern and SEM images. EDAX spectra proved the high purity of the composites. Here, different biological properties change with the calcination temperature for different shapes, sizes and structures of the nanocomposite. Nanomaterial calcined at 750 °C provides the best anti-microbial activity against Escherichia coli, Salmonella typhimurium, Shigella flexneri (gram-negative), Bacillus subtilis and Bacillus megaterium (gram-positive) bacterial strain at 300 µg/mL concentration. The nanomaterial with calcination temperatures of 300 °C and 450 °C provided better antioxidant properties.

Solution behaviour prevailing in L-Arginine and L-Histidine in aqueous Tetrabutylammonium methanesulphonate (TBMS) has been studied to investigate the mode of interactions by means of density (ρ), viscosity (η), surface tension (σ), refractive index (nD) and electrolytic conductivity at three different temperatures. The nature of interactions occurring in the solutions have been elucidated on the basis of apparent molar volume (Фv0), limiting molar expansivities (ФE0), viscosity A- and B- coefficients, molar refraction (RM) and concentration measurements. Molar conductance (Ʌ), obtained, so, describe the nature of solute–solute and solute–solvent interactions in the solution mixtures. Using Gaussian 09 W quantum chemical package, optimum energies with the optimised geometries of molecular assembly for (TBMS + L-Arginine) and (TBMS + L-Histidine) systems and also critical micelle concentration (CMC) values were calculated and found supportive to the practical outcomes that show the solute–solvent interactions prevailing between the TBMS (IL) and amino acids; L-Arginine and L-Histidine are dominant over the solute–solute interactions. Furthermore, L-Arginine shows a higher extent of interaction that is also influenced by the concentrations and temperatures in comparison to L-Histidine in aqueous IL solutions. The theoretical observations of the study determining Δμ10≠, Δμ20≠, ΔH0≠, and TΔS0≠ also imply the presence of strong interactions in the systems. The various types of interactions between amino acids which are the protein backbone, in presence of ionic liquids would develop a many-dimensional challenge in the field of solution chemistry. Studies of such systems could be advanced further using the correlated outcomes of the investigation.